API Keys vs JWT Tokens: When to Use Each Credential

TL;DR

• API keys identify clients (apps, servers, webhooks). They are simple strings that never expire unless you revoke them.
• JWT tokens carry claims about users or sessions and usually expire within minutes.
• Many production systems use both: an API key authenticates the client, and JWTs authorize individual end users.

Strengths of API Keys

1. Simplicity – a header such as x-api-key: sk_live_... is trivial to validate.
2. Partitioning – you can issue keys per environment, partner, or integration.
3. Server-to-server fit – background jobs and webhooks rarely have a human to authorize, so keys win.

Where JWTs Shine

1. Self-contained claims – scopes, tenant IDs, and expiration timestamps are part of the payload.
2. Stateless verification – HS256 or RS256 signatures allow horizontally scaled APIs to validate requests without a database lookup.
3. User context – mobile or SPA front ends can refresh tokens silently without prompting for a password.

Hybrid Architecture Example

1. Your partner signs requests with an API key; the gateway checks quotas and origin.
2. The downstream service expects a JWT in the Authorization header to represent the final user.
3. Both credentials are logged and can be revoked independently, limiting the blast radius of a leaked key.

Migration Tips

• Keep API keys short-lived by rotating them automatically via your developer portal.
• When introducing JWTs, publish a /.well-known/jwks.json or HS256 secret fingerprint so integrators can validate tokens locally.
• Monitor for mixed usage (API key with no JWT or vice versa) and block requests that fall outside allowed flows.

Need fresh credentials? Start with the API Key Generator for client keys and the JWT Secret Key Generator for signing tokens.